OBJECTIVES: (1)To examine the national trend of pediatric atypical antipsychotic (AAP) use in the US. (2)To identify primary mental disorders associated with AAPs. (3)To estimate the strength of independent association between patient/provider characteristics and AAP use.  METHODS: Data source came from the National Ambulatory Medical Care Survey (NAMCS) and the National Hospital Ambulatory Medical Care Survey (NHAMCS). First, average AAP visit rates among 4- to 18 year-old patients between 1993 and 2010 were estimated. Second, data from 2007 to 2010 were combined and analyzed to identify primary mental disorders related to AAP prescription. Third, a logistic regression model was developed having the presence of AAP prescription as the dependent variable and patient/provider characteristics as explanatory variables. Odds ratios (ORs) with associated 95% confidence intervals (CIs) were estimated. RESULTS: Outpatient visits including an AAP prescription among 4- to 18-year-old patients significantly increased between 1993 and 2010 in the U.S., and over 65 percent of those visits did not have diagnoses for FDA approved AAP indications. During 2007-2010, the most common mental disorder was attention-deficit hyperactivity disorder (ADHD), accounting for 24 percent of total pediatric AAP visits. Among visits with ADHD diagnosis, those with Medicaid as payer (OR, 1.66, 95% CI 1.01-2.75), comorbid mental disorders (e.g., psychoses OR 3.34, 95% CI 1.35-8.26) and multiple prescriptions (4 or more prescriptions OR 4.48, 95% CI 2.08-9.64) were more likely to have an AAP prescription. CONCLUSIONS: The off-label use of AAPs in children and adolescents is prevalent in the US. Our study raises questions about the potential misuse of AAPs in the population.